It is based on the Soviet 7.62×39 mm round, but with the neck expanded to fit a 9.3mm bullet. Initial design of the cartridge began in the 1940s by a team of 27 unknown members. Final design was completed by N. Zabelin, L. Dvoryaninova and Y. Frolov of the TsNIITochMash in the 1980s. The intent was to create a subsonic cartridge for suppressed firearms for special forces units that had more power, range and penetration than pistol cartridges usually used in such weapons. The commercial Wolf Ammunition bullet weighs 276 grain, or 18 grams, a little more than double that of the normal 123 gr 7.62×39 mm round, and has only subsonic muzzle velocity. This reduced velocity does not produce a sonic boom, and also limits the muzzle energy and effective range of a weapon when compared to high velocity rounds normally used in rifles. The round has an optimistic effective lethal range of 400 to 530 meters and a maximum penetration of up to 10 mm of steel. Like the 5.45×39mm cartridge, 9×39mm SP-5 features an airpocket in the tip, which increases its tendency to yaw or "keyhole" upon impact, thus increasing soft tissue damage in human targets, and also the armor-piercing SP6 cartridge are more effective against light armored, vehicle, or light barrier targets, although neither of those are imported into the USA.
Variants
SP-5 - The SP-5 was developed by Nikolai Zabelin. It is a conventional lead core FMJ bullet, developed for accuracy. SP-5UZ - The SP-5UZ is an SP-5 variant with an increased charge intended for a factory-specific strength testing of the weapons. SP-6 - The SP-6 was developed by Yuri Frolov. It has a hardened metal armor-piercing core. It can penetrate of steel at 500 meters or of steel, of titanium or 30 layers of Kevlar at 200 meters. At 100 meters it penetrates of steel, while retaining enough power to inflict damage to a soft target behind it. SP-6UCh - The SP-6Uch is an SP-6 variant intended for training. PAB-9 - The SP-6's bullet is expensive, so an attempt was made to make a lower-cost version of the cartridge. The PAB-9 used a stamped rather than machined steel core. It sacrificed too much performance to be usable., its usage is prohibited. SPP - The SPP is a sniper round with increased penetration. BP - The BP is an armor-piercing round.
The "Vladikavkaz 9x39mm Subsonic Round Restriction" signed during the Syrian Civil War restricted the use of these munitions in certain areas of the conflict due to safety concerns with the rounds high effectiveness against unarmored and armored targets, which was believed that if used posed a significant chance of over penetration that would cause civilian casualties.
